Cognitive impairment and low physical activity are the components of frailty more strongly associated with disability.

Objective: To determine the association of the five frailty criteria from the Cardiovascular Health Study, as well as cognitive impairment, with prevalent disability for the instrumental (IADL) and basic activities of daily living (ADL).
Design: Cross-sectional study of 475 community-dwelling subjects aged 70 and older, participating in the Mexican Study of Nutritional and Psychosocial Markers of Frailty.
Measurements: Six probable frailty criteria were considered: weight loss, poor endurance, low physical activity, slowness, weakness, and cognitive impairment. The association of each component of frailty for IADL and ADL disability as main outcomes was determined constructing multivariate logistic regression analyses. Final models were adjusted by socio-demographic factors and the presence of the other five frailty components as covariates.
Results: Mean age of participants was 78.1 (SD=6.2). The unadjusted results showed that each of the components of frailty, except weight loss, was associated with both IADL and ADL disability. However, after adjustment, only low physical activity [Odds ratio (OR) =3.27; 95% CI=1.56 to 6.85] and cognitive impairment (OR=2.06; 95% CI=1.04 to 4.06) remain independently associated with IADL disability. Regarding ADL disability, only a lower physical activity (OR=7.72; 95% CI=1.28 to 46.46) was associated with this outcome, whereas cognitive impairment was marginally associated but was not statistically significant (OR=5.45; 95% CI=0.91 to 32.57).
Conclusions: Cognitive impairment and low physical activity are the main contributing factors of frailty phenotype to disability. Better understanding the independent contribution of each frailty subdimension to the different adverse-health outcomes may help to provide a more adequate management of frail elderly.